Camera lens

ABSTRACT

The present disclosure provides a camera lens which has good optical properties and a full image angle of above 76°, is ultra-thin, and comprises five lenses having a high luminous flux F number. The camera lens includes, from an object side to an image side, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a positive refractive power and a fifth lens having a negative refractive power. The camera lens satisfies specified relational expressions.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Japanese Patent ApplicationNo. JP2018-021669, filed on Feb. 9, 2018, the content of which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a camera lens, and in particular to acamera lens which is suitable for use in a modular camera for a mobilephone, a WEB camera, or the like using a camera element such as ahigh-pixel CCD or CMOS, has good optical properties, is ultra-thin tothe point that total track length (TTL)/image height (IH) is ≤1.45, hasa full image angle (hereinafter, indicated as 2ω) of above 76°, andconsists of five lenses having bright F-number (hereinafter referred toas Fno) of less than 2.25.

BACKGROUND

In recent years, various types of camera devices equipped with a cameraelement such as a CCD and CMOS and others have been widely used. Alongwith the development of miniature and high performance camera elements,the ultrathin wide-angle camera lenses with good optical properties andbright Fno are needed.

The technology related to the camera lens composed of five ultrathinwide-angle lenses with good optical properties and bright Fno is beingdeveloped gradually. The camera lens is composed of five lenses, whichare lined up from an object side in an order as follows: a first lenshaving a positive refractive power, a second lens having a negativerefractive power, a third lens having a positive refractive power, afourth lens having a positive refractive power and a fifth lens having anegative refractive power.

The camera lens disclosed in the embodiments of Patent Document 1(listed as below) is the above-described camera lens constituted of fivelenses. However, since the refractive power distribution of the firstlens and the third lens and the shapes of the first lens and the secondlens are not sufficient, the luminance and ultra-thinning level is notsufficient.

The camera lens disclosed in Embodiment 1 of Patent Document 2 (listedas below) is the above-described camera lens constituted of five lenses.However, since the refractive power distribution of the first lens andthe third lens and the shape of the third lens are not sufficient, theultra-thinning level is not sufficient.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Patent Application Laid-Open No.2015-225246;

Patent Document 2: Japanese Patent Application Laid-Open No.2015-225102.

BRIEF DESCRIPTION OF DRAWINGS

Many aspects of the exemplary embodiment can be better understood withreference to the following drawings. The components in the drawings arenot necessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the present disclosure. Moreover,in the drawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a structural diagram of a camera lens LA according to anembodiment of the present disclosure.

FIG. 2 is a structural diagram of the above-described camera lens LAaccording to Embodiment 1.

FIG. 3 is a diagram of a spherical aberration of the camera lens LA ofEmbodiment 1.

FIG. 4 is a diagram of a magnification chromatic aberration of thecamera lens LA of Embodiment 1.

FIG. 5 is a diagram of field curvature and distortion of the camera lensLA of Embodiment 1.

FIG. 6 is a structural diagram of the above-described camera lens LAaccording to Embodiment 2.

FIG. 7 is a diagram of a spherical aberration of the camera lens LA ofEmbodiment 2.

FIG. 8 is a diagram of a magnification chromatic aberration of thecamera lens LA of Embodiment 2.

FIG. 9 is a diagram of field curvature and distortion of the camera lensLA of Embodiment 2.

DESCRIPTION OF EMBODIMENTS

An embodiment of a camera lens according to the present disclosure willbe described with reference to the drawings. A diagram showing astructure of the camera lens according to the embodiments of the presentdisclosure is as shown in FIG. 1. The camera lens LA has a five-lenssystem which includes a first lens L1, a second lens L2, a third lensL3, a fourth lens L4 and a fifth lens L5, which are arranged from anobject side toward an image side. A glass plate GF is provided betweenthe fifth lens L5 and an imaging plane. The glass plate GF can be aglass plate using a cover glass or having an IR cut-off filter and otherfunctions. In addition, the glass plate GF may not be provided betweenthe fifth lens L5 and the imaging plane.

The first lens L1 is a lens having a positive refractive power, thesecond lens L2 is a lens having a negative refractive power, the thirdlens L3 is a lens having a positive refractive power, the fourth lens L4is a lens having a positive refractive power, and the fifth Lens L5 is alens having a negative refractive power. With respect to the lenssurfaces of these five lenses, it is preferable to make them be asphericsurfaces in order to satisfactorily correct various aberrations.

The camera lens LA satisfies the following relational expressions (1) to(4):0.80≤f1/f≤0.90  (1)15.00≤f3/f≤25.00  (2)0.80≤(R3+R4)/(R3−R4)≤1.50  (3)−50.00≤(R5+R6)/(R5−R6)≤−25.00  (4),in which:f denotes an overall focal length of the lens system,f1 denotes a focal length of the first lens,f3 denotes a focal length of the third lens,R3 denotes a curvature radius of the object side surface of the secondlens,R4 denotes a curvature radius of the image side surface of the secondlens;R5 denotes a curvature radius of the object side surface of the thirdlens; andR6 denotes a curvature radius of the image side surface of the thirdlens.

The relational expression (1) specifies the positive refractive power ofthe first lens L1. When it is out of the range of the relationalexpression (1), 2ω≥76° and it is not preferable because it is difficultto make the camera lens ultra-thin and have a bright Fno.

Furthermore, it is further preferable to set the numerical range of therelational expression (1) as the numerical range of the followingrelational expression (1-A):0.82≤f1/f≤0.85  (1-A),

The relational expression (2) specifies the positive refractive power ofthe third lens L3. When it is out of the range of the relationalexpression (2), 2ω≥76° and it is not preferable because it is difficultto make the camera lens ultra-thin and have a bright Fno.

Furthermore, it is further preferable to set the numerical range of therelational expression (2) as the numerical range of the followingrelational expression (2-A):18.00≤f3/f≤22.00  (2-A).

The relational expression (3) specifies the shape of the second lens L2.When it is out of the range of the relational expression (3), 2ω≥76° andit is not preferable because it is difficult to make the camera lensultra-thin and have a bright Fno.

Furthermore, it is further preferable to set the numerical range of therelational expression (3) as the numerical range of the followingrelational expression (3-A):1.20≤(R3+R4)/(R3−R4)≤1.40  (3-A).

The relational expression (4) specifies the shape of the third lens L3.When it is out of the range of the relational expression (4), 2ω≥76° andit is not preferable because it is difficult to make the camera lensultra-thin and have a bright Fno.

Furthermore, it is further preferable to set the numerical range of therelational expression (4) as the numerical range of the followingrelational expression (4-A):−40.00≤(R5+R6)/(R5−R6)≤−30.00  (4-A).

The second lens L2 is a lens having negative refractive power, whichsatisfies the following relational expressions (5):−2.50≤f2/f≤−1.50  (5),in whichf denotes an overall focal length of the lens system,

f2 denotes a focal length of the second lens.

The relational expression (5) specifies the negative refractive power ofthe second lens L2. When it is out of the range of the relationalexpression (5), 2ω≥76° and it is not preferable because it is difficultto make the camera lens ultra-thin and have a bright Fno.

Furthermore, it is further preferable to set the numerical range of therelational expression (5) as the numerical range of the followingrelational expression (5-A):−2.00≤f2/f≤−1.70  (5-A).

The first lens L1 is a lens having a positive refractive power, andsatisfies the following relational expression (6):−2.00≤(R1+R2)/(R1−R2)≤−1.20  (6),whereinR1 denotes the curvature radius of the object side surface of the firstlens, andR2 denotes the curvature radius of the image side surface of the firstlens.

The relational expression (6) specifies the shape of the first lens L1.When it is out of the range of the relational expression (6), 2ω≥76° andit is not preferable because it is difficult to make the camera lensultra-thin and have a bright Fno.

Furthermore, it is further preferable to set the numerical range of therelational expression (6) as the numerical range of the followingrelational expression (6-A):−1.80≤(R1+R2)/(R1−R2)≤−1.40  (6-A).

Each of the five lenses constituting the camera lens LA satisfies thestructure and relational expression described above, and it is possibleto obtain a camera lens which has good optical properties and a fullimage angle of above 76°, is ultra-thin, and has a bright Fno value.

EMBODIMENTS

f: the overall focal length of the camera lens LA;

f1: the focal length of the first lens L1;

f2: the focal length of the second lens L2;

f3: the focal length of the third lens L3;

f4: the focal length of the fourth lens L4;

f5: the focal length of the fifth lens L5;

Fno: F number;

2ω: full image angle;

S1: aperture;

R: the curvature radius of the optical surface, which is the centercurvature radius of the lens;

R1: the curvature radius of the object side surface of the first lensL1;

R2: the curvature radius of the image side surface of the first lens L1;

R3: the curvature radius of the object side surface of the second lensL2;

R4: the curvature radius of the image side surface of the second lensL2;

R5: the curvature radius of the object side surface of the third lensL3;

R6: the curvature radius of the image side surface of the third lens L3;

R7: the curvature radius of the object side surface of the fourth lensL4;

R8: the curvature radius of the image side surface of the fourth lensL4;

R9: the curvature radius of the object side surface of the fifth lensL5;

R10: the curvature radius of the image side surface of the fifth lensL5;

R11: the curvature radius of the object side surface of the glass plateGF;

R12: the curvature radius of the image side surface of the glass plateGF;

d: the center thickness of the lens or the distance between the lenses;

d0: the axial distance from the open aperture S1 to the object sidesurface of the first lens L1;

d1: the center thickness of the first lens L1;

d2: the axial distance from the image side surface of the first lens L1to the object side surface of the second lens L2;

d3: the center thickness of the second lens L2;

d4: the axial distance from the image side surface of the second lens L2to the object side surface of the third lens L3;

d5: the center thickness of the third lens L3;

d6: the axial distance from the image side surface of the third lens L3to the object side surface of the fourth lens L4;

d7: the center thickness of the fourth lens L4;

d8: the axial distance from the image side surface of the fourth lens L4to the object side surface of the fifth lens L5;

d9: the center thickness of the fifth lens L5;

d10: the axial distance from the image side surface of the fifth lens L5to the object side surface of the glass plate GF;

d11: the center thickness of the glass plate GF;

d12: the axial distance from the image side surface of the glass plateGF to the imaging plane;

nd: the refractive index of line d;

nd1: the refractive index of line d of the first lens L1;

nd2: the refractive index of line d of the second lens L2;

nd3: the refractive index of line d of the third lens L3;

nd4: the refractive index of line d of the fourth lens L4;

nd5: the refractive index of line d of the fifth lens L5;

nd6: the refractive index of line d of the glass plate GF;

v: the Abbe number;

v 1: the Abbe number of the first lens L1;

v 2: the Abbe number of the second lens L2;

v 3: the Abbe number of the third lens L3;

v 4: the Abbe number of the fourth lens L4;

v 5: the Abbe number of the fifth lens L5;

v 6: the Abbe number of the glass plate GF;

TTL: optical length (the axial distance from the object side surface ofthe first lens L1 to the imaging plane); and

LB: the axial distance from the image side surface of the fifth lens L5to the imaging plane (including the thickness of the glass plate GF).y=(x ² /R)/[1+{1−(k+1)(x ² /R ²)}^(1/2)]+A4x ⁴ +A6x ⁶ +A8x ⁸ +A10x ¹⁰+A12x ¹² +A14x ¹⁴ +A16x ¹⁶  (7)

R is the axial curvature radius, k is the conic coefficient, and A4, A6,A8, A10, A12, A14, and A16 are aspheric coefficients.

For the sake of convenience, the aspheric surface represented by therelational expression (7) is used as an aspheric surface of each of thelenses. However, the present disclosure is not limited to the asphericsurface represented by the relational expression (7).

Embodiment 1

FIG. 2 is a structural diagram of the camera lens LA of Embodiment 1.Each of the first lens L1 to the fifth lens L5 constituting the cameralens LA of Embodiment 1 has a curvature radius of R of the object sideand image side, a center thickness of the lens or a distance d betweenthe lenses, a refractive index nd, and an Abbe number v Abbe numberTable 1, and a conic coefficient k and an aspheric coefficient as shownin Table 2.

TABLE 1 R d nd ν d S1 ∞ d0= −0.260 R1 1.43313 d1= 0.523 nd1 1.5439 ν 155.95 R2 7.98153 d2= 0.080 R3 35.45109 d3= 0.208 nd2 1.6510 ν 2 21.51 R43.92575 d4= 0.346 R5 3.86859 d5= 0.256 nd3 1.6510 ν 3 21.51 R6 4.12226d6= 0.495 R7 −7.43123 d7= 0.714 nd4 1.5439 ν 4 56.12 R8 −1.09064 d8=0.279 R9 −4.91442 d9= 0.406 nd5 1.5352 ν 5 56.12 R10 1.32189 d10= 0.500R11 ∞ d11= 0.210 nd6 1.5168 ν 6 64.17 R12 ∞ d12= 0.397

TABLE 2 conic coefficient aspheric coefficient k A4 A6 A8 A10 A12 A14A16 R1  2.3460E−01 −1.0735E−02 1.2204E−02 −2.4845E−01   9.0516E−01−1.6314E+00 1.4251E+00 −5.3578E−01 R2  9.5914E+00 −1.2411E−01−2.6034E−02  1.0494E+00 −2.4358E+00  1.8534E+00 −1.8993E−01  −2.0532E−01R3 −5.9093E+00 −1.7141E−01 3.3605E−01 6.8241E−01 −2.5394E+00  2.3768E+00−4.8423E−01  −1.2969E−01 R4  1.2126E+01 −1.0881E−01 2.9260E−016.0366E−01 −3.3874E+00  6.4715E+00 −6.1424E+00   2.4507E−00 R5 1.2006E+01 −2.6289E−01 1.0185E−01 −2.3552E−01   7.4799E−01 −1.4279E+001.3876E+00 −5.5398E−01 R6 −8.1210E+00 −1.3902E−01 −1.0486E−02 7.1114E−02 −4.2435E+02  9.6060E−03 2.2510E−02 −1.1314E−02 R7  1.6283E+01 3.4032E−02 −6.3020E−02  3.2514E−02 −5.8052E−00 −7.4559E−05 −2.3234E−02  1.3775E−04 R8 −5.1085E+00 −1.3019E−01 1.9060E−01 −2.4159E−01  1.9365E−01 −8.1474E−02 1.6802E−02 −1.3574E−03 R9 −2.4180E−01−9.9204E−02 −9.1419E−03  3.2518E−02 −1.0585E−02  1.1722E−03 5.0000E−06−6.4314E−06 R10 −8.2200E+00 −1.0907E−01 5.1881E−02 −2.0063E−02  5.2021E−03 −8.5937E−04 7.9337E−05 −3.0356E−06

Table 5 below shows the numerical values defined in Embodiments 1 and 2and the numerical values corresponding to the parameters specified bythe relational expressions (1) to (6).

As shown in Table 5, Embodiment 1 satisfies the relational expressions(1) to (6).

The spherical aberration of the camera lens LA of Embodiment 1 is asshown in FIG. 3, the magnification chromatic aberration of magnificationthereof is as shown in FIG. 4, and the field curvature and thedistortion are as shown in FIG. 5. Furthermore, the field curvature S inFIG. 5 is the field curvature for the sagittal imaging plane, and T isthe field curvature for the meridianal imaging plane, and the sameapplies to Embodiment 2. As can be seen from FIGS. 3 to 5, the cameralens LA of Embodiment 1 has 2ω=79.4°, TTL/IH=1.403, Fno=2.20 and 2ω≥76°and is ultra-thin, thereby resulting in a bright Fno and good opticalproperties.

Embodiment 2

FIG. 6 is a structural diagram of the camera lens LA of Embodiment 2.Each of the first lens L1 to the fifth lens L5 constituting the cameralens LA of Embodiment 2 has a curvature radius of R of the object sideand image side, a center thickness of the lens or a distance d betweenthe lenses, a refractive index nd, and an Abbe number v as shown inTable 3, and a conic coefficient k and an aspheric coefficient as shownin Table 4.

TABLE 3 R d nd ν d S1 ∞ d0= −0.260 R1 1.42589 d1= 0.523 nd1 1.5439 ν 155.95 R2 8.05286 d2= 0.080 R3 34.03873 d3= 0.208 nd2 1.6510 ν 2 21.51 R43.90337 d4= 0.363 R5 3.83965 d5= 0.248 nd3 1.6510 ν 3 21.51 R6 4.09141d6= 0.492 R7 −6.84046 d7= 0.717 nd4 1.5439 ν 4 56.12 R8 −1.09907 d8=0.286 R9 −5.05385 d9= 0.398 nd5 1.5352 ν 5 56.12 R10 1.33317 d10= 0.500R11 ∞ d11= 0.210 nd6 1.5168 ν 6 64.17 R12 ∞ d12= 0.389

TABLE 4 conic coefficient aspheric coefficient k A4 A6 A8 A10 A12 A14A16 R1  2.2551E−01 −1.2431E−02 1.3372E−02 −2.4711E−01   9.0417E−01−1.6340E+00 1.4240E+00 −5.3056E−01 R2  6.4218E+00 −1.2600E−01−1.9085E−02  1.0545E+00 −2.4365E+00  1.8495E+00 −1.9122E−01  −1.9987E−01R3 −1.5000E−02 −1.6901E−01 3.3595E−01 6.8575E−01 −2.5326E+00  2.3826E+00−4.8450E−01  −1.3931E−01 R4  1.2292E+01 −1.0510E−01 2.8557E−016.0612E−01 −3.3840E+00  6.4676E+00 −6.1467E+00   2.4632E+00 R5 1.1252E+01 −2.6677E−01 7.0207E−01 −2.3818E−01   7.4461E−01 −1.4274E+007.3915E+00 −5.5370E−01 R6 −1.0146E+01 −1.4116E−01 −1.2180E−02 7.1194E−02 −4.2162E−02  9.2642E−03 2.2174E−02 −1.0437E−02 R7  1.6659E+01 3.3363E−02 −6.2830E−02  3.2796E−02 −5.6474E−03 −1.1231E−05 −2.1683E−04  1.3668E−04 R8 −5.1274E+00 −1.3074E−01 1.9047E−01 −2.4165E−01  1.9363E−01 −8.1479E−02 1.6803E−02 −1.3549E−03 R9 −2.6160E−01−9.9197E−02 −9.1468E−03  3.2523E−02 −1.0532E−02  1.1729E−03 5.1733E−06−6.3844E−06 R10 −8.1562E+00 −1.0994E−01 5.1955E−02 −2.0057E−02  5.2028E−03 −8.5919E−04 7.9388E−05 −3.0236E−06

As shown in Table 5, Embodiment 2 satisfies the relational expressions(1) to (6).

The spherical aberration of the camera lens LA of Embodiment 2 is asshown in FIG. 7, the magnification chromatic aberration of magnificationthereof is as shown in FIG. 8, and the field curvature and thedistortion are as shown in FIG. 9. As can be seen from FIGS. 7 to 9, thecamera lens LA of Embodiment 2 has 2ω=79.1°, TTL/IH=1.403, is ultra-thinto Fno=2.20 and has 2ω≥76°, thereby resulting in a bright Fno goodoptical properties.

TABLE 5 Embodiment 1 Embodiment 2 Notes f1/f 0.840 0.831 Exp(1) f3/f18.587 18.539 Exp(2) (R3 + R4)/(R3 − R4) 1.249 1.259 Exp(3) (R5 +R6)/(R5 − R6) −31.500 −31.502 Exp(4) f2/f −1.829 −1.824 Exp(5) (R1 +R2)/(R1 − R2) −1.438 −1.430 Exp(6) Fno 2.20 2.20 2ω 79.4 79.1 TTL/IH1.403 1.403 f 3.717 3.725 f1 3.124 3.097 f2 −6.800 −6.792 f3 69.09269.048 f4 2.258 2.304 f5 −1.903 −1.929 TTL 4.414 4.414 LB 1.107 1.099 IH3.147 3.147

LIST OF REFERENCE SIGNS

-   LA: camera lens-   S1: open aperture-   L1: the first lens-   L2: the second lens-   L3: the third lens-   L4: the fourth lens-   L5: the fifth lens-   GF: glass plate-   R: the curvature radius of the optical surface, which is the center    curvature radius of the lens-   R1: the curvature radius of the object side surface of the first    lens L1-   R2: a curvature radius of the image side surface of the first lens    L1-   R3: a curvature radius of the object side surface of the second lens    L2-   R4: a curvature radius of the image side surface of the second lens    L2-   R5: a curvature radius of the object side surface of the third lens    L3-   R6: a curvature radius of the image side surface of the third lens    L3-   R7: a curvature radius of the object side surface of the fourth lens    L4-   R8: a curvature radius of the image side surface of the fourth lens    L4-   R9: a curvature radius of the object side surface of the fifth lens    L5-   R10: a curvature radius of the image side surface of the fifth lens    L5-   R11: a curvature radius of the object side surface of the glass    plate GF-   R12: a curvature radius of the image side surface of the glass plate    GF-   d: the center thickness of the lens or the distance between the    lenses-   d0: the distance from the open aperture S1 to the object side    surface of the first lens L1-   d1: the center thickness of the first lens L1-   d2: the axial distance from the image side surface of the first lens    L1 to the object side surface of the second lens L2-   d3: the center thickness of the second lens L2-   d4: the axial distance from the image side surface of the second    lens L2 to the object side surface of the third lens L3-   d5: the center thickness of the third lens L3-   d6: the axial distance from the image side surface of the third lens    L3 to the object side surface of the fourth lens L4-   d7: the center thickness of the fourth lens L4-   d8: the axial distance from the image side surface of the fourth    lens L4 to the object side surface of the fifth lens L5-   d9: the center thickness of the fifth lens L5-   d10: the axial distance from the image side surface of the fifth    lens L5 to the object side surface of the glass plate GF-   d11: the center thickness of the glass plate GF-   d12: the axial distance from the image side surface of the glass    plate GF to the imaging plane.

What is claimed is:
 1. A camera lens, comprising, from an object side toan image side: a first lens having a positive refractive power, a secondlens having a negative refractive power, a third lens having a positiverefractive power, a fourth lens having a positive refractive power and afifth lens having a negative refractive power, the camera lenssatisfying following relational expressions (1) to (4):0.80≤f1/f≤0.90  (1)15.00≤f3/f≤25.00  (2)0.80≤(R3+R4)/(R3−R4)≤1.50  (3)−50.00≤(R5+R6)/(R5−R6)≤−25.00  (4), wherein f denotes an overall focallength of the camera lens, f1 denotes a focal length of the first lens,f3 denotes a focal length of the third lens, R3 denotes a curvatureradius of an object side surface of the second lens, R4 denotes acurvature radius of an image side surface of the second lens; R5 denotesa curvature radius of an object side surface of the third lens; and R6denotes a curvature radius of an image side surface of the third lens.2. The camera lens according to claim 1, wherein: the camera lenssatisfies following relational expression (5):−2.50≤f2/f≤−1.50  (5), wherein f2 denotes a focal length of the secondlens.
 3. The camera lens according to claim 1, wherein: the camera lenssatisfies following relational expression (6):−2.00≤(R1+R2)/(R1−R2)≤−1.20  (6), wherein R1 denotes a curvature radiusof an object side surface of the first lens, and R2 denotes a curvatureradius of an image side surface of the first lens.